Best approximation and moduli of smoothness: computation and equivalence theorems

• Autores: Sergey Tikhonov
• Localización: Journal of approximation theory, ISSN 0021-9045, Vol. 153, Nº 1, 2008, págs. 19-39
• Idioma: inglés
• DOI: 10.1016/j.jat.2007.05.006
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• Resumen

  • In this paper we investigate the trigonometric series with the ß-general monotone coefficients. First, we study the uniform convergence criterion. The estimates of best approximations and moduli of smoothness of the series in uniform metrics are obtained in terms of coefficients. These results imply several important relations between moduli of smoothness of different orders (in particular, Marchaud-type inequality) and best approximations.